Endocrine Abstracts

Insulinoma is a tumour of the endocrine pancreas, usually benign, with an annual incidence of 1–2 new cases per million population. We describe a case of Insulinoma complicated by the simultaneous development of diabetes.

A 72year old lady had episodes of funny turns and confusion following her meal. She had lost a stone in weight over 6–8 months. There was no history of sulphonylurea ingestion. Examination revealed low BMI and no evidence of rashes. A prolonged oral glucose tolerance test revealed a hyperglycemia in the diabetic range in one hour and symptomatic hypoglycemia in three hours. C-peptide test revealed raised baseline value, which did not suppress with insulin. Glucagon levels were marginally raised. CT scan of the abdomen revealed 2.6 cm × 2.2 cm lesion in the body of the pancreas. The tumour was excised. Immunocytochemistry showed weak positive staining for Glucagon and strong positive staining for Insulin. Post-operatively her blood sugar returned to normal.

Symptomatic hypoglycemia relieved by food and weight gain (30%) are the features of Insulinoma. In contrast, weight loss (90%) and mild diabetes (80%) are the salient features of glucagonoma. Our patient had substantial weight loss and new onset diabetes at the seventh decade. With the marginal rise in the glucagon levels and a weakly positive staining for glucagon in imunocytochemistry, it is arguable that our patient might have had coexistent glucagonoma. However, our patient did not have the characteristic skin rash of glucagonoma, nor the glucagons levels were high enough to substantiate the diagnosis. Interestingly, the huge fluctuation in her blood glucose associated with disabling hypoglycemia had completely normalised after the surgery and she started gaining weight as well.

Expression of multiple hormones in a pancreatic endocrine neoplasm can sometimes cloud the clinical picture. Accurate diagnosis and appropriate intervention can reverse the symptoms.